how to implement a Server with 2003 SBS as a member of an existing domain

on a network with a Server running financial applications and is the domain server, I need to implement another server for a GIS application manipulating data from the financial applications. I was not able to implement the new server with win-2003-SBS which started sending messages all over the network that there is a licensing conflict and displayng a message that the server will shutdown in 30 minutes. a potential suggested cause is that this “windows” does not allow the server to be a member in an existing domain – it wants to be the domain controller. so what can I do to overcome this obstacle.